Given that most kits I see from the early days of the modern drumkit had a single rack tom, isn't it the other way around? So the question should be: Why is it the fashion to add another rack tom and push your ride further away? Many live bands I see do this?
In any case, it's just a matter of taste. I have one rack tom and two floor toms because I want to have three toms, and I prefer the sound and power of large toms for my style of playing and my genre (I don't really want four toms, since my style doesn't require it, so it would only add complexity to my setup and require me to carry more stuff to gigs). Nothing to do with fashion, it's just a matter of what I prefer.
Of course, there are fashions and trends in drumming too, like with anything else. The 80s had extravagant music with extravagant kits; the 90s had minimalist music with small kits and the 2000s had something in between, often with large drums and cymbals but not a huge number of drums and cymbals. On top of that, each musical genre will often have its own fashions (prog rock drummers often use large kits because they need many sound sources for those complex fills and grooves, while jazz drummers need fewer pieces but are often extremely specific when it comes to how those pieces need to sound, etc).